Line 6 Spider 3 150 'black box syndrome'. Anyone found a definitive cure?

[allante666]

Hi. Took in P/X a Line6 Spider 3 150 (2x12 combo). It was all working exactly as it should with the exception that the display just showed the 8 black boxes. After Googling around I found this is a very common symptom and all but one of the threads I read either ended up dumping it or sending it back to Line6 for repair.
One guy said he had found the 3.3 volt rail to be very low and replacing the regulator (which he said was a 5 pin SMD so I'm not sure his was the same amp?) cured it so I checked my 3.3 volt rail and it holds steady and ripple free at 3.27 which I reckon is near enough!.

nothing I did including factory reset etc would change the display. I had the display out to make sure it wasnt just dirty contacts on the rubber conductor, checked the ribbon cables, checked for dry joints etc., nothing made a difference. So, figured I would slap it back together and either leave it for a rainy day or use the two celestions out of it for something else.

Put it together, turned it on and the darn thing works perfectly and I cant make it do otherwise! As you all know this is a very bittersweet result as I cant trust it now so still need to know what has happened. Ive tried poking it with chopsticks, drumsticks, baseball bats... no different. Just wont go wrong now.
I notice as it switches on it just briefly flashes the 8 boxes before it displays the text so was it something not booting up correctly and was getting stuck at the black box point? The amp itself worked fine an dyou could still change all the presets you just couldnt see which they were.

Has anyone ever found out definitively about this one? I have no schematic for it btw I can only find the spider 75 watt which doesn't have the display. The spider 4 has a different display altogether.

Any comments appreciated!

[allante666]

UPdate! Found it!
It was one of the pins on the display board wasn't being grabbed by the spring clip inside the plug of the ribbon cable properly. No amount of poking would have found it as it had to be making contact when it was switched on. once on it made no difference if it made contact or not it was obviously just needed at switch on.

i pulled the wire from the ribbon and extended it around the pcb to solder direct to the pin.

Didn't have time to work out what it did but if it helps anyone in the future it was the 5th wire in from the red tracer wire on the ribbon that goes from the front panel to the display panel (display end in my case)

[Jazz P Bass]

Depending on the lCD, wether or not it has the LCD +/- contrast pins, the 5th pin would be either R/W or DB5 or DB3.

R/W is in Write mode if it is low.
So if it was a missing or intermittant connection, that may have been an issue.
(not too sure if a floating pin would register as a low.)

The missing (or floating) data buss DB3 or DB5 would probably scramble the display.
In what way, I am not sure.

[allante666]

Is that the same pinout though as the ribbon cable? The cable goes to the pcb before it gets to the LCD. Anyone have a schematic for this amp?

[Jazz P Bass]

Don't know if it is the same.

That is a generic LCD pinout.